I want to create a matrix for N groups and T time periods. For each combination of T-N, I want to have a random number of lines.
The random number of lines for each N-T is given by round(runif(1,2,4)).
The goal is to have as input :
set.seed(123)
ngroup = 2
tperiod = 2
Using round(runif(1,2,4)) 4 times gives 3,4,3,4, so the output should have :
And as the output should be :
mat = cbind(c(1,1,1,1,1,1,1,2,2,2,2,2,2,2), c(1,1,1,2,2,2,2,1,1,1,2,2,2,2))
mat
[,1] [,2]
[1,] 1 1
[2,] 1 1
[3,] 1 1
[4,] 1 2
[5,] 1 2
[6,] 1 2
[7,] 1 2
[8,] 2 1
[9,] 2 1
[10,] 2 1
[11,] 2 2
[12,] 2 2
[13,] 2 2
[14,] 2 2
Where the 1st column is the group ID, and the 2nd the time ID.
Option 1: index the result of expand.grid.
set.seed(123)
N <- 1:2
T <- 1:2
combos <- length(N)*length(T)
expand.grid(list(T = T, N = N))[rep.int(1:combos, round(runif(combos, 2, 4))),2:1]
#> N T
#> 1 1 1
#> 1.1 1 1
#> 1.2 1 1
#> 2 1 2
#> 2.1 1 2
#> 2.2 1 2
#> 2.3 1 2
#> 3 2 1
#> 3.1 2 1
#> 3.2 2 1
#> 4 2 2
#> 4.1 2 2
#> 4.2 2 2
#> 4.3 2 2
Option 2: rep.int(rep(.
set.seed(123)
r <- round(runif(length(N)*length(T), 2, 4))
data.frame(
N = rep.int(rep(N, each = length(T)), r),
T = rep.int(rep(T, length(N)), r)
)
#> N T
#> 1 1 1
#> 2 1 1
#> 3 1 1
#> 4 1 2
#> 5 1 2
#> 6 1 2
#> 7 1 2
#> 8 2 1
#> 9 2 1
#> 10 2 1
#> 11 2 2
#> 12 2 2
#> 13 2 2
#> 14 2 2